The Configuration and Reconfiguration utilities are usually used together to change the contents of the logical configuration. The pdeconfig utility invokes the vconfig utility to map the logical configuration (for example, AMPs) to the physical configuration (for example, disk storage).

Note: Data rows are associated with AMPs by the hash code of a data row and the hash bucket of an AMP. For more information, see "Analyzing Row Distribution" on page 2-51.

You associate PEs defined in the configuration with one or more channel-connected clients or Gateway-connected networks that also are defined in the configuration.

AMPs in a configuration can be related to other AMPs through cluster assignments. Clusters are a technique used with fallback to increase data protection and availability. For details on their assignment, use, and effect on performance, see "AMP Clustering and Fallback" on page 7-32.

Configuration Activities

When Teradata RDBMS is initialized, the System Initializer (sysinit) process builds a default configuration map that describes the target AMP involved in sysinit. This configuration is stored in both the current and new configuration maps.

When the database is operational, the Configuration utility describes the complete system in the new configuration map.

As the system grows and changes, use Configuration to revise the new configuration map to reflect these types of changes to the system:

• Add and delete hosts and AMP and PE vprocs.

• Move data rows from an existing AMP or group of AMPs to a new AMP or group of AMPs (usually on another node). This allows the logical removal of the existing AMP(s) after the data has been successfully moved.

• Move an existing PE or group of PEs to a new PE or group of PEs on another node. This allows for the logical removal of the existing PEs after the PEs have been successfully moved.

• Change host assignments.

• Change cluster assignments.

Note: It is a good idea to add AMPs before changing clusters. If you do not add AMPs, be sure you have enough permanent space before beginning the reassignment. (CurrentPerm should be less than 53% of total MaxPerm; see "Changing Cluster Assignments" on page 7-35.)

Warning: If Reconfiguration determines there is not enough space to reassign clusters as specified, the process stops. The only way to recover is to reinitialize the system, which will lose all data.

Reconfiguration usually involves adding or removing hardware, but sometimes does not (for example, changing cluster assignments).

After Configuration builds a new configuration map, the Reconfiguration utility redefines the system configuration according to the new map. Reconfiguration copies the new configuration map to the current configuration map and (if AMPs were added) automatically redistributes the data rows.

Note: If Reconfiguration is in the middle of hash map calculations (for row redistribution) and a Teradata RDBMS reset or system crash occurs, the utility might not be able to restart and an error message might say that AMP nn contains unexpected tables. You can clean out the new AMP and resume, as instructed in Teradata RDBMS Utilities.

pdeconfig Activities

Before you add a vproc to the current configuration, you first must define it to the physical configuration. Once you delete a vproc from the current configuration, you then must remove it from the physical configuration.

The pdeconfig utility invokes vconfig to perform these tasks. The vconfig utility maps the virtual elements of AMPs and PEs to the physical elements, such as disks and host channel or Ethernet controllers.

Warning: Only start pdeconfig on the package distribution node (PDN). (This usually is the lowest-numbered node in the TPA.) Running pdeconfig on any other node could result in the loss of all your data. Please contact the PDE team in the TSC if you have any question about using this utility.

Moving Vprocs and Data Rows for Hardware Upgrades

When you need to replace an outdated node or array or a down disk, you can use the MOVE commands (or ADD/MOVE combination) of the Configuration, Reconfiguration, and pdeconfig utilities. MOVE greatly reduces the manual and row redistribution effort required to:

• Remove first-generation nodes and associated storage from a coexistence system when adding a third-generation node.